VSCode LSP MCP

🔍 Overview

VSCode LSP MCP is a Visual Studio Code extension that exposes Language Server Protocol (LSP) features through the Model Context Protocol (MCP).

Extension ID: cjl.lsp-mcp — open Extensions (Ctrl+Shift+X / Cmd+Shift+X) and search for cjl.lsp-mcp to find this plugin precisely.

This allows AI assistants and external tools to utilize VSCode's powerful language intelligence capabilities without direct integration.

[!TIP] Using Neovim? See vv-mcp.nvim, the sibling implementation that exposes Neovim LSP clients and live editor context through MCP.

🌟 Why This Extension?

Large language models like Claude and Cursor struggle to understand your codebase accurately because:

• They rely on regex patterns to find symbols, leading to false matches
• They can't analyze import/export relationships properly
• They don't understand type hierarchies or inheritance
• They have limited code navigation capabilities

This extension bridges that gap, providing AI tools with the same code intelligence that VSCode uses internally!

⚙️ Features

• 🔄 LSP Bridge: Converts LSP features into MCP tools
• 🤖 VS Code Copilot integration: Registers the local MCP server directly with VS Code Chat / Copilot
• 🔌 Multi-Instance Broker: One stable MCP endpoint discovers and routes requests across all open VS Code windows
• 🧠 25 LSP operations covering navigation, diagnostics, document metadata, symbols, call hierarchy, transactional rename, and safe Code Actions
• ☕ Java dependency source: Get decompiled Java class source via jdt:// URI (from jdtls), so AI can read library implementations
• 📄 Dual output format: JSON for machine processing, Markdown for LLM-friendly reading

🛠️ Exposed MCP Tools

LSP operations

All operations are invoked through the single execute_lsp MCP tool with a unified input format:

• operation — which LSP operation to execute
• uri — file path or URI string (supports both plain paths and file:///jdt:// URIs)
• line — line number (1-based, matching editor display). Required for position-dependent operations
• character — character offset (1-based, matching editor display). Required for position-dependent operations
• newName / renameId — used by the three-stage rename flow
• actionKind / actionId — filter and continue the Code Action transaction flow
• query — required only for workspace_symbols
• symbolKinds, includeDeclaration, includeExternal, pathPattern, severities, sources, codes — optional result filters applied before maxResults
• startLine, endLine — optional inclusive range for inlay_hints
• callId — returned by call hierarchy operations for recursive traversal
• instanceId — optional instance returned by list_instances; takes precedence over automatic path routing

1-based positions: Both input and output use 1-based line/character values, matching what your editor displays. VS Code shows Ln 9, Col 16 → pass line: 9, character: 16. Output positions can be used directly as input for the next call — no conversion needed.

Multi-instance routing

The extension starts one lightweight internal endpoint per VS Code window and registers it with a shared broker. External clients keep using a single MCP URL. The broker selects an instance in this order:

1. Exact instanceId, when provided
2. Longest workspace-root prefix matching the input file path
3. The only active instance, when no path can identify one

If two windows open the same project, routing is intentionally rejected as ambiguous until the caller passes instanceId. The registry contains no public credentials and stale window records expire automatically.

The first multi-instance release supports local desktop workspaces and file: resources. Remote SSH, WSL, Dev Containers, and virtual workspaces are not yet advertised as supported.

Workspace tools

For example, the built-in TypeScript provider updates relative imports and barrel exports when a referenced .ts or .tsx file is renamed. The exact companion edits remain language-provider dependent, so inspect diagnostics after applying a resource rename.

📋 Configuration

🔗 Integration with AI Tools

VS Code Copilot

No mcp.json setup is required. After the extension starts, it registers the local LSP MCP server with VS Code through an MCP server definition provider.

Use MCP: List Servers or the chat tools picker in VS Code to enable or manage the LSP MCP Server.

Cursor

Config file: ~/.cursor/mcp.json (e.g. %USERPROFILE%\.cursor\mcp.json on Windows)

{
  "mcpServers": {
    "lsp-mcp": {
      "url": "http://127.0.0.1:9527/mcp"
    }
  }
}

OpenCode

Config file: ~/.config/opencode/opencode.jsonc

{
  "mcp": {
    "lsp-mcp": {
      "type": "remote",
      "url": "http://127.0.0.1:9527/mcp",
      "enabled": true
    }
  }
}

Claude Code

Config file: ~/.claude.json

{
  "mcpServers": {
    "lsp-mcp": {
      "type": "http",
      "url": "http://127.0.0.1:9527/mcp"
    }
  }
}

Gemini | IFlow

Config file: ~/.gemini/settings.json

{
  "mcpServers": {
    "lsp-mcp": {
      "type": "streamable-http",
      "httpUrl": "http://127.0.0.1:9527/mcp"
    }
  }
}

Codex

Config file: ~/.codex/config.toml

[mcp_servers.lsp-mcp]
url = "http://127.0.0.1:9527/mcp"

Roo Code

{
  "mcpServers": {
    "lsp-mcp": {
      "type": "streamable-http",
      "url": "http://127.0.0.1:9527/mcp",
      "disabled": false
    }
  }
}

💻 Development

• Clone the repository
• Run pnpm install
• Run pnpm run update to generate metadata
• Press F5 to start debugging